Batch Transform - breast cancer prediction with lowel level SDK.ipynb failed CI

Link to the notebook:
https://github.com/aws/amazon-sagemaker-examples/blob/master/sagemaker_batch_transform/batch_transform_associate_predictions_with_input/Batch Transform - breast cancer prediction with lowel level SDK.ipynb

Error:

---------------------------------------------------------------------------
Exception encountered at "In [5]":
---------------------------------------------------------------------------
ParamValidationError Traceback (most recent call last)
in
2 data_train.to_csv(train_file,index=False,header=False)
3 with open(train_file,'rb') as data:
----> 4 boto3.Session().resource('s3').Bucket(bucket).upload_fileobj(data,os.path.join(prefix,'train',train_file))
5
6 validation_file = 'validation_data.csv'

/opt/conda/lib/python3.7/site-packages/boto3/s3/inject.py in bucket_upload_fileobj(self,

[...]

Invalid bucket name "": Bucket name must match the regex "^[a-zA-Z0-9.\-_]{1,255}$" or be an ARN matching the regex "^arn:(aws).*:s3:[a-z\-0-9]+:[0-9]{12}:accesspoint[/:][a-zA-Z0-9\-]{1,63}$|^arn:(aws).*:s3-outposts:[a-z\-0-9]+:[0-9]{12}:outpost[/:][a-zA-Z0-9\-]{1,63}[/:]accesspoint[/:][a-zA-Z0-9\-]{1,63}$"